The invention relates to motion correction, and more particularly, to motion correction by the use of image enhancement techniques.
Motion quality errors in printing systems often result in objectionable image quality for customers. For example, in an electronic imaging machine having a moving photosensitive surface and a raster scanning system or print array to project black and white pixels onto the photosensitive surface, image error can be introduced if there are changes in the speed of movement of the photosensitive surface. A higher relative speed of the photosensitive surface results in the beams across the surface or print array projections becoming spread apart. A lower relative speed of the photosensitive surface results in the beams across the surface or print array projections becoming squeezed together. The effect on image quality, for example, can be degraded image elements, for example, black lines that are much narrower or broader than desired for acceptable quality.
In the prior art, more precise speed control of moving elements such as photoreceptors in reproduction machines, is accomplished by motor and speed control devices such as servo mechanisms. The difficulty with this alternative is that servo mechanisms are relatively complex and expensive solutions to the problem. Also, adding additional hardware is often very awkward and almost precludes the possibility of retrofitting existing machines.
It would be desirable to be able to provide a relatively simple and economical system to compensate for image degradation due to motion errors in the imaging system. It is an object, therefore, of the present invention to provide a new and improved system for compensating for motion errors that degrade image quality. Another object of the present invention is to compensate for motion errors that degrade image quality by modifying the modulation of a scanning beam across a photosensitive surface in response to changes in speed of the photosensitive surface. Other advantages of the present invention will become apparent as the following description proceeds, and the features characterizing the invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.